Stent delivery under direct visualization

ABSTRACT

A tissue manipulation system comprises a reconfigurable hood structure with a distal end. The structure has a low profile delivery configuration and an expanded deployed configuration which defines an open area bounded at least in part by the structure and by an interface surface extending across the hood structure distal end. The open area is in fluid communication with an environment external to the hood structure. The system also includes a catheter in communication with the open area such that introduction of a fluid through the catheter purges the open area of bodily fluid. The interface surface is slanted relative to the catheter longitudinal axis when the hood structure is in the expanded deployed configuration. The system also includes an imaging element positioned on the hood structure such that the open area is visualized through the fluid by the element.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority to U.S. Prov. Pat. App.61/026,795 filed Feb. 7, 2008, which is incorporated herein by referencein its entirety.

FIELD OF THE INVENTION

The present invention relates generally to stent delivery systems whichmay be used to place one or more stents along a lesion. Moreparticularly, the present invention relates to methods and apparatus forthe delivery of one or more stents along a lesion, such as an ostiallesion or along a stenosed region (e.g., caused by atheroscleroticplaque) at various locations, for instance along the coronary vessels,renal arteries, etc., while directly visualizing the tissue region.

BACKGROUND OF THE INVENTION

Conventional devices for visualizing interior regions of a body lumenare known. For example, ultrasound devices have been used to produceimages from within a body in vivo. Ultrasound has been used both withand without contrast agents, which typically enhance ultrasound-derivedimages.

Other conventional methods have utilized catheters or probes havingposition sensors deployed within the body lumen, such as the interior ofa cardiac chamber. These types of positional sensors are typically usedto determine the movement of a cardiac tissue surface or the electricalactivity within the cardiac tissue. When a sufficient number of pointshave been sampled by the sensors, a “map” of the cardiac tissue may begenerated.

Another conventional device utilizes an inflatable balloon which istypically introduced intravascularly in a deflated state and theninflated against the tissue region to be examined. Imaging is typicallyaccomplished by an optical fiber or other apparatus such as electronicchips for viewing the tissue through the membrane(s) of the inflatedballoon. Moreover, the balloon must generally be inflated for imaging.Other conventional balloons utilize a cavity or depression formed at adistal end of the inflated balloon. This cavity or depression is pressedagainst the tissue to be examined and is flushed with a clear fluid toprovide a clear pathway through the blood.

However, such imaging balloons have many inherent disadvantages. Forinstance, such balloons generally require that the balloon be inflatedto a relatively large size which may undesirably displace surroundingtissue and interfere with fine positioning of the imaging system againstthe tissue. Moreover, the working area created by such inflatableballoons are generally cramped and limited in size. Furthermore,inflated balloons may be susceptible to pressure changes in thesurrounding fluid. For example, if the environment surrounding theinflated balloon undergoes pressure changes, e.g., during systolic anddiastolic pressure cycles in a beating heart, the constant pressurechange may affect the inflated balloon volume and its positioning toproduce unsteady or undesirable conditions for optimal tissue imaging.Additionally, imaging balloons are subject to producing poor or blurredtissue images if the balloon is not firmly pressed against the tissuesurface because of intervening blood between the balloon and tissue.

Accordingly, these types of imaging modalities are generally unable toprovide desirable images useful for sufficient diagnosis and therapy ofthe endoluminal structure, due in part to factors such as dynamic forcesgenerated by the natural movement of the heart. Moreover, anatomicstructures within the body can occlude or obstruct the image acquisitionprocess. Also, the presence and movement of opaque bodily fluids such asblood generally make in vivo imaging of tissue regions within the heartdifficult.

Other external imaging modalities are also conventionally utilized. Forexample, computed tomography (CT) and magnetic resonance imaging (MRI)are typical modalities which are widely used to obtain images of bodylumens such as the interior chambers of the heart. However, such imagingmodalities fail to provide real-time imaging for intra-operativetherapeutic procedures. Fluoroscopic imaging, for instance, is widelyused to identify anatomic landmarks within the heart and other regionsof the body. However, fluoroscopy fails to provide an accurate image ofthe tissue quality or surface and also fails to provide forinstrumentation for performing tissue manipulation or other therapeuticprocedures upon the visualized tissue regions. In addition, fluoroscopyprovides a shadow of the intervening tissue onto a plate or sensor whenit may be desirable to view the intraluminal surface of the tissue todiagnose pathologies or to perform some form of therapy on it.

In one particular treatment, intravascular stents are commonly used tomaintain the patency of a vascular lumen. Conventional stent deliverysystems typically employ intravascular ultrasound (IVUS) for selectingthe appropriate stent and placing it at the site of lesions, e.g.,ostial lesions. However, such assessment and placement methods are notaccurate. For instance, the treatment site may be located in the rightcoronary artery immediately adjacent to the ostium in the aortic wall.In such instances, it is often difficult to accurately position anintravascular stem such that the stent does not extend too far proximalto the ostium. Accuracy in placing the stent at the desired location istypically affected by, e.g., limited visualization of the ostium,angulations of the aorto-coronary segment, and the difficulties in theplacement of the guiding catheter.

Accurate positioning of the stent along the ostial lesion isparticularly desirable because (a) if the stent is placed too proximalto the ostium, the protrusion of the stent into the aortic lumen cancause thrombus or other complications; and (b) if the stent is placedtoo distal to the ostium, the stent may not be able to subdue the ostiallesion completely thereby resulting in low success rate and highincidence of re-stenosis or recurrence of arterial blockage.

Thus, methods and/or apparatus which are able to allow for accuratepositioning of the stent relative to the ostial lesion is highlydesirable.

SUMMARY OF THE INVENTION

A tissue imaging and manipulation apparatus that may be utilized forprocedures within a body lumen, such as the heart, in whichvisualization of the surrounding tissue is made difficult, if notimpossible, by medium contained within the lumen such as blood, isdescribed below. Generally, such a tissue imaging and manipulationapparatus comprises an optional delivery catheter or sheath throughwhich a deployment catheter and imaging hood may be advanced forplacement against or adjacent to the tissue to be imaged.

The deployment catheter may define a fluid delivery lumen therethroughas well as an imaging lumen within which an optical imaging fiber orassembly may be disposed for imaging tissue. When deployed, the imaginghood may be expanded into any number of shapes, e.g., cylindrical,conical as shown, semi-spherical, etc., provided that an open area orfield is defined by the imaging hood. The open area is the area withinwhich the tissue region of interest may be imaged. The imaging hood mayalso define an atraumatic contact lip or edge for placement or abutmentagainst the tissue region of interest. Moreover, the distal end of thedeployment catheter or separate manipulatable catheters may bearticulated through various controlling mechanisms such as push-pullwires manually or via computer control

The deployment catheter may also be stabilized relative to the tissuesurface through various methods. For instance, inflatable stabilizingballoons positioned along a length of the catheter may be utilized, ortissue engagement anchors may be passed through or along the deploymentcatheter for temporary engagement of the underlying tissue.

In operation, after the imaging hood has been deployed, fluid may bepumped at a positive pressure through the fluid delivery lumen until thefluid fills the open area completely and displaces any blood from withinthe open area. The fluid may comprise any biocompatible fluid, e.g.,saline, water, plasma, Fluorinert™, etc., which is sufficientlytransparent to allow for relatively undistorted visualization throughthe fluid. The fluid may be pumped continuously or intermittently toallow for image capture by an optional processor which may be incommunication with the assembly.

In an exemplary variation for imaging tissue surfaces within a heartchamber containing blood, the tissue imaging and treatment system maygenerally comprise a catheter body having a lumen defined therethrough,a visualization element disposed adjacent the catheter body, thevisualization element having a field of view, a transparent fluid sourcein fluid communication with the lumen, and a barrier or membraneextendable from the catheter body to localize, between the visualizationelement and the field of view, displacement of blood by transparentfluid that flows from the lumen, and an instrument translatable throughthe displaced blood for performing any number of treatments upon thetissue surface within the field of view. The imaging hood may be formedinto any number of configurations and the imaging assembly may also beutilized with any number of therapeutic tools which may be deployedthrough the deployment catheter.

More particularly in certain variations, the tissue visualization systemmay comprise components including the imaging hood, where the hood mayfurther include a membrane having a main aperture and additionaloptional openings disposed over the distal end of the hood. Anintroducer sheath or the deployment catheter upon which the imaging hoodis disposed may further comprise a steerable segment made of multipleadjacent links which are pivotably connected to one another and whichmay be articulated within a single plane or multiple planes. Thedeployment catheter itself may be comprised of a multiple lumenextrusion, such as a four-lumen catheter extrusion, which is reinforcedwith braided stainless steel fibers to provide structural support. Theproximal end of the catheter may be coupled to a handle for manipulationand articulation of the system.

To provide visualization, an imaging element such as a fiberscope orelectronic imager such as a solid state camera, e.g., CCD or CMOS, maybe mounted, e.g., on a shape memory wire, and positioned within or alongthe hood interior. A fluid reservoir and/or pump (e.g., syringe,pressurized intravenous bag, etc.) may be fluidly coupled to theproximal end of the catheter to hold the translucent fluid such assaline or contrast medium as well as for providing the pressure toinject the fluid into the imaging hood.

In treating tissue regions which are directly visualized, as describedabove, one particular treatment involves deploying a stent within avessel lumen or ostium while under direct visualization. An introducersheath may be introduced into the patient's body utilizing conventionalapproaches such that the sheath is advanced intravascularly through theaorta where a guidewire may be advanced through the sheath and into,e.g., the right coronary artery. The treatment may be affected not onlywithin and around the right coronary artery, but also the left coronaryartery, left anterior descending artery, left circumflex artery, or anyother vessel accessible by the assembly. As the guidewire is positionedwithin, e.g., the vessel lumen, the deployment catheter and hood may bedeployed from the sheath and advanced along the guidewire until thecircumference of the hood contacts against or in proximity to theostium. Once the hood is in contact against the ostium, the clearingfluid may be introduced within the open area of the hood to purge theblood from the hood interior to provide a clear field through which animaging element positioned within or along the hood may visualizethrough to view the underlying tissue surrounding the ostium and atleast a portion of the vessel wall extending into the lumen.

A stent delivery assembly having an inflatable balloon in an un-inflatedlow-profile configuration and a stent crimped or otherwise positionedupon the balloon may be advanced through the catheter and distally outfrom the hood until the stent assembly is positioned in proximity oradjacent to, e.g., an ostial lesion, which is to be treated. The imagingelement may be used to directly visualize at least partially into thelumen as the purged clearing fluid exits the hood and down through thelumen to provide an image of the lesion to be treated.

With the stent assembly desirably positioned and confirmed by directvisualization, the balloon may be inflated to expand the stent over thelesion, also while under visualization. In other variations, the ballooncarrying the stent may be integrated with a visualization balloonpositioned proximally of the stent assembly rather than a hood. Theballoon may be subsequently deflated and then retracted back into thehood and the catheter leaving the deployed stent positioned desirablywithin the lumen. The imager may be used to visually confirm thedeployment and positioning of the stent within the lumen.

In determining the size of the ostial lesion to be treated, the imagingcapabilities of the hood may be utilized for optimally treating thepatient by directly measuring not only the lesion but also the diameterof the vessel lumen for determining an appropriate stent to be deployedas the diameter of the vessel as well as the axial length of the lesionmay affect the shape and size of the stent.

One example utilizes a measurement catheter having a number ofgradations with known distances which may be advanced through the hoodand into the lumen. With the purging fluid introduced through the hoodand into the lumen, the markings on the catheter may be viewed andcompared to the lesion directly to provide a more accurate measurementof the lesion length than provided by a fluoroscopic image alone. Inother variations, expandable baskets or members each having a knownexpanded diameter may be positioned along a support catheter andadvanced distally from the hood and into the lumen to measure a diameterof the vessel interior. The inner diameter of the vessel can thus becalculated by considering the diameter of the member which is blockedfrom entering the ostium. With the calculated length and diameter of thevessel and lesion to be treated, an appropriate stent may be selectedfor placement at the ostial lesion.

In yet another variation, a deployment catheter may utilize a hoodhaving an angled interface which is angled relative to the catheter. Theasymmetric slanted hood may be used to facilitate navigation within theaorta as the hood may be better able to engage against a tissue regionor ostium and establish visualization without the need to steer and/orarticulate the catheter shaft perpendicularly within the narrow aortalumen.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A shows a side view of one variation of a tissue imaging apparatusduring deployment from a sheath or delivery catheter.

FIG. 1B shows the deployed tissue imaging apparatus of FIG. 1A having anoptionally expandable hood or sheath attached to an imaging and/ordiagnostic catheter.

FIG. 1C shows an end view of a deployed imaging apparatus.

FIGS. 2A and 2B show one example of a deployed tissue imager positionedagainst or adjacent to the tissue to be imaged and a flow of fluid, suchas saline, displacing blood from within the expandable hood.

FIGS. 3A and 3B show examples of various visualization imagers which maybe utilized within or along the imaging hood.

FIGS. 4A and 4B show perspective and end views, respectively, of animaging hood having at least one layer of a transparent elastomericmembrane over the distal opening of the hood.

FIGS. 5A and 5B show perspective and end views, respectively, of animaging hood which includes a membrane with an aperture definedtherethrough and a plurality of additional openings defined over themembrane surrounding the aperture.

FIG. 6 illustrates an example of a system configured for visualizationand stent delivery.

FIGS. 7A to 7C show partial cross-sectional views of deploying a stentintravascularly within a coronary artery while under directvisualization.

FIGS. 8A to 8C show partial cross-sectional detail views of a stentassembly introduced and deployed within a vessel while under directvisualization.

FIG. 9A shows a partial cross-sectional view of a measurement catheterdeployed within a vessel for directly measuring a length of a lesion.

FIG. 9B shows a partial cross-sectional view of one or more measurementbaskets or expandable members which may be utilized to measure an innerdiameter of the vessel.

FIGS. 10A to 10C illustrate side views of measurement baskets orexpandable members which may be deployed sequentially in determining theinner diameter of a vessel.

FIGS. 11A to 11E illustrate another variation where a stent may bepositioned upon a balloon integrated with a visualization balloonpositioned proximally of the stent for deployment within a vessel.

FIGS. 12A and 12B show a side view of a hood variation which utilizes anangled interface and the angled hood deployed within the body against anostium.

DETAILED DESCRIPTION OF THE INVENTION

A tissue-imaging and manipulation apparatus described herein is able toprovide real-time images in vivo of tissue regions within a body lumensuch as a heart, which is filled with blood flowing dynamicallytherethrough and is also able to provide intravascular tools andinstruments for performing various procedures upon the imaged tissueregions. Such an apparatus may be utilized for many procedures, e.g.,facilitating transseptal access to the left atrium, cannulating thecoronary sinus, diagnosis of valve regurgitation/sienosis,valvuloplasty, atrial appendage closure, arrhythmogenic focus ablation,among other procedures.

One variation of a tissue access and imaging apparatus is shown in thedetail perspective views of FIGS. 1A to 1C. As shown in FIG. 1A, tissueimaging and manipulation assembly 10 may be delivered intravascularlythrough the patient's body in a low-profile configuration via a deliverycatheter or sheath 14. In the case of treating tissue, it is generallydesirable to enter or access the left atrium while minimizing trauma tothe patient. To non-operatively effect such access, one conventionalapproach involves puncturing the intra-atrial septum from the rightatrial chamber to the left atrial chamber in a procedure commonly calleda transseptal procedure or septostomy. For procedures such aspercutaneous valve repair and replacement, transseptal access to theleft atrial chamber of the heart may allow for larger devices to beintroduced into the venous system than can generally be introducedpercutaneously into the arterial system.

When the imaging and manipulation assembly 10 is ready to be utilizedfor imaging tissue, imaging hood 12 may be advanced relative to catheter14 and deployed from a distal opening of catheter 14, as shown by thearrow. Upon deployment, imaging hood 12 may be unconstrained to expandor open into a deployed imaging configuration, as shown in FIG. 1B.Imaging hood 12 may be fabricated from a variety of pliable orconformable biocompatible material including but not limited to, e.g.,polymeric, plastic, or woven materials. One example of a woven materialis Kevlar® (E. I. du Pont de Nemours, Wilmington, Del.), which is anaramid and which can be made into thin, e.g., less than 0.001 in.,materials which maintain enough integrity for such applicationsdescribed herein. Moreover, the imaging hood 12 may be fabricated from atranslucent or opaque material and in a variety of different colors tooptimize or attenuate any reflected lighting from surrounding fluids orstructures, i.e., anatomical or mechanical structures or instruments. Ineither case, imaging hood 12 may be fabricated into a uniform structureor a scaffold-supported structure, in which case a scaffold made of ashape memory alloy, such as Nitinol, or a spring steel, or plastic,etc., may be fabricated and covered with the polymeric, plastic, orwoven material. Hence, imaging hood 12 may comprise any of a widevariety of barriers or membrane structures, as may generally be used tolocalize displacement of blood or the like from a selected volume of abody lumen or heart chamber. In exemplary embodiments, a volume withinan inner surface 13 of imaging hood 12 will be significantly less than avolume of the hood 12 between inner surface 13 and outer surface 11.

Imaging hood 12 may be attached at interface 24 to a deployment catheter16 which may be translated independently of deployment catheter orsheath 14. Attachment of interface 24 may be accomplished through anynumber of conventional methods. Deployment catheter 16 may define afluid delivery lumen 18 as well as an imaging lumen 20 within which anoptical imaging fiber or assembly may be disposed for imaging tissue.When deployed, imaging hood 12 may expand into any number of shapes,e.g., cylindrical, conical as shown, semi-spherical, etc., provided thatan open area or field 26 is defined by imaging hood 12. The open area 26is the area within which the tissue region of interest may be imaged.Imaging hood 12 may also define an atraumatic contact lip or edge 22 forplacement or abutment against the tissue region of interest. Moreover,the diameter of imaging hood 12 at its maximum fully deployed diameter,e.g., at contact lip or edge 22, is typically greater relative to adiameter of the deployment catheter 16 (although a diameter of contactlip or edge 22 may be made to have a smaller or equal diameter ofdeployment catheter 16). For instance, the contact edge diameter mayrange anywhere from 1 to 5 times (or even greater, as practicable) adiameter of deployment catheter 16. FIG. 1C shows an end view of theimaging hood 12 in its deployed configuration. Also shown are thecontact lip or edge 22 and fluid delivery lumen 18 and imaging lumen 20.

As seen in the example of FIGS. 2A and 2B, deployment catheter 16 may bemanipulated to position deployed imaging hood 12 against or near theunderlying tissue region of interest to be imaged, in this example aportion of annulus A of mitral valve MV within the left atrial chamber.As the surrounding blood 30 flows around imaging hood 12 and within openarea 26 defined within imaging hood 12, as seen in FIG. 2A, theunderlying annulus A is obstructed by the opaque blood 30 and isdifficult to view through the imaging lumen 20. The translucent fluid28, such as saline, may then be pumped through fluid delivery lumen 18,intermittently or continuously, until the blood 30 is at leastpartially, and preferably completely, displaced from within open area 26by fluid 28, as shown in FIG. 2B.

Although contact edge 22 need not directly contact the underlyingtissue, it is at least preferably brought into close proximity to thetissue such that the flow of clear fluid 28 from open area 26 may bemaintained to inhibit significant backflow of blood 30 back into openarea 26. Contact edge 22 may also be made of a soft elastomeric materialsuch as certain soft grades of silicone or polyurethane, as typicallyknown, to help contact edge 22 conform to an uneven or rough underlyinganatomical tissue surface. Once the blood 30 has been displaced fromimaging hood 12, an image may then be viewed of the underlying tissuethrough the clear fluid 30. This image may then be recorded or availablefor real-time viewing for performing a therapeutic procedure. Thepositive flow of fluid 28 may be maintained continuously to provide forclear viewing of the underlying tissue. Alternatively, the fluid 28 maybe pumped temporarily or sporadically only until a clear view of thetissue is available to be imaged and recorded, at which point the fluidflow 28 may cease and blood 30 may be allowed to seep or flow back intoimaging hood 12. This process may be repeated a number of times at thesame tissue region or at multiple tissue regions.

FIG. 3A shows a partial cross-sectional view of an example where one ormore optical fiber bundles 32 may be positioned within the catheter andwithin imaging hood 12 to provide direct in-line imaging of the openarea within hood 12. FIG. 3B shows another example where an imagingelement 34 (e.g., CCD or CMOS electronic imager) may be placed along aninterior surface of imaging hood 12 to provide imaging of the open areasuch that the imaging element 34 is off-axis relative to a longitudinalaxis of the hood 12, as described in further detail below. The off-axisposition of element 34 may provide for direct visualization anduninhibited access by instruments from the catheter to the underlyingtissue during treatment.

In utilizing the imaging hood 12 in any one of the procedures describedherein, the hood 12 may have an open field which is uncovered and clearto provide direct tissue contact between the hood interior and theunderlying tissue to effect any number of treatments upon the tissue, asdescribed above. Yet in additional variations, imaging hood 12 mayutilize other configurations. An additional variation of the imaginghood 12 is shown in the perspective and end views, respectively, ofFIGS. 4A and 4B, where imaging hood 12 includes at least one layer of atransparent elastomeric membrane 40 over the distal opening of hood 12.An aperture 42 having a diameter which is less than a diameter of theouter lip of imaging hood 12 may be defined over the center of membrane40 where a longitudinal axis of the hood intersects the membrane suchthat the interior of hood 12 remains open and in fluid communicationwith the environment external to hood 12. Furthermore, aperture 42 maybe sized, e.g., between 1 to 2 mm or more in diameter and membrane 40can be made from any number of transparent elastomers such as silicone,polyurethane, latex, etc. such that contacted tissue may also bevisualized through membrane 40 as well as through aperture 42.

Aperture 42 may function generally as a restricting passageway to reducethe rate of fluid out-flow from the hood 12 when the interior of thehood 12 is infused with the clear fluid through which underlying tissueregions may be visualized. Aside from restricting out-flow of clearfluid from within hood 12, aperture 42 may also restrict externalsurrounding fluids from entering hood 12 too rapidly. The reduction inthe rate of fluid out-flow from the hood and blood in-flow into the hoodmay improve visualization conditions as hood 12 may be more readilyfilled with transparent fluid rather than being filled by opaque bloodwhich may obstruct direct visualization by the visualizationinstruments.

Moreover, aperture 42 may be aligned with catheter 16 such that anyinstruments (e.g., piercing instruments, guidewires, tissue engagers,etc.) that are advanced into the hood interior may directly access theunderlying tissue uninhibited or unrestricted for treatment throughaperture 42. In other variations wherein aperture 42 may not be alignedwith catheter 16, instruments passed through catheter 16 may stillaccess the underlying tissue by simply piercing through membrane 40.

In an additional variation, FIGS. 5A and 5B show perspective and endviews, respectively, of imaging hood 12 which includes membrane 40 withaperture 42 defined therethrough, as described above. This variationincludes a plurality of additional openings 44 defined over membrane 40surrounding aperture 42. Additional openings 44 may be uniformly sized,e.g., each less than 1 mm in diameter, to allow for the out-flow of thetranslucent fluid therethrough when in contact against the tissuesurface. Moreover, although openings 44 are illustrated as uniform insize, the openings may be varied in size and their placement may also benon-uniform or random over membrane 40 rather than uniformly positionedabout aperture 42 in FIG. 5B. Furthermore, there are eight openings 44shown in the figures although fewer than eight or more than eightopenings 44 may also be utilized over membrane 40.

Additional details of tissue imaging and manipulation systems andmethods which may be utilized with apparatus and methods describedherein are further described, for example, in U.S. patent applicationSer. No. 11/259,498 filed Oct. 25, 2005 (U.S. Pat. Pub. No. 2006/0184048A1, which is incorporated herein by reference in its entirety.

As the assembly allows for ablation of tissue directly visualizedthrough hood 12, FIG. 6 illustrates an example of a system configuredfor visualization and stent delivery. As shown in visualization assembly50, hood 12 and deployment catheter 16 are coupled to handle 52. Fluidreservoir 54, shown in this example as a saline-filled bag reservoir,may be attached through handle 52 to provide the clearing fluid and/orablation medium. An optical imaging assembly 56 coupled to an imagingelement 34 positioned within or adjacent to hood 12 may extendproximally through handle 52 and be coupled to imaging processorassembly 58 for processing the images detected within hood 12. The videoprocessor assembly 58 may process the detected images within hood 12 fordisplay upon video display 60. Handle 52 may further incorporate adelivery channel or port 62 through which a stent delivery assembly maybe introduced for deployment of one or more stents into the patient'sbody through the deployment catheter 16 and hood 12.

One example for deploying a stent while under direct visualization isshown in the partial cross-sectional views of FIGS. 7A to 7C. Introducersheath 14 may be introduced into the patient's body utilizingconventional approaches such that the sheath 14 is advancedintravascularly through the descending aorta DA and aortic arch AC andinto the ascending aorta AA, where a guidewire 70 may be advancedthrough sheath 14 and into, e.g., the right coronary artery RCA.Treatment may be affected not only within and around the right coronaryartery RCA, but also the left coronary artery LCA, left anteriordescending artery, left circumflex artery, or any other vesselaccessible by the assembly. As the guidewire 70 is positioned within,e.g., the lumen 72 of RCA as shown in FIG. 7A, deployment catheter 16and hood 12 may be deployed from sheath 14 and advanced along guidewire70, as shown in FIG. 7B, until the circumference of hood 12 contactsagainst or in proximity to ostium OS. Guidewire 70 may be omitted fromthe procedure, if so desired.

Once hood 12 is in contact against the ostium OS, the clearing fluid maybe introduced within the open area of hood 12 to purge the blood fromthe hood interior to provide a clear field through which an imagingelement positioned within or along hood 12 may visualize through to viewthe underlying tissue surrounding the ostium OS and at least a portionof the vessel wall extending into lumen 72.

As illustrated in the detail partial cross-sectional views of FIGS. 8Ato 8C, with hood 12 positioned against or in proximity to ostium OS andthe visual field cleared to provide visual imaging by imager 34, a stentdelivery assembly 80 having an inflatable balloon 82 in an un-inflatedlow-profile configuration and a stent 84 crimped or otherwise positionedupon balloon 82 may be advanced through catheter 16 and distally outfrom hood 12 until stent assembly 80 is positioned in proximity oradjacent to, e.g., an ostial lesion 86, which is to be treated, as shownin FIG. 8A. Imager 34 may be used to directly visualize at leastpartially into lumen 72 as the purged clearing fluid exits hood 12 anddown through lumen 72 to provide an image of the lesion 86 to betreated.

With stent assembly 80 desirably positioned and confirmed by directvisualization, balloon 82 may be inflated to expand stent 84 over lesion86, as shown in FIG. 8B, also while under visualization. Balloon 82 maybe subsequently deflated and then retracted back into hood 12 andcatheter 16 leaving the deployed stent 84 positioned desirably withinlumen 72. Imager 34 may be used to visually confirm the deployment andpositioning of stent 84 within lumen 72, as shown in FIG. 8C.

In determining the size of the ostial lesion to be treated, the imagingcapabilities of the hood 12 may be utilized for optimally treating thepatient by directly measuring not only the lesion but also the diameterof the vessel lumen for determining an appropriate stent to be deployedas the diameter of the vessel as well as the axial length of the lesionmay affect the shape and size of the stent.

One example is illustrated in the partial cross-sectional area of FIG.9A, which shows hood 12 positioned against ostium OS with imager 34visualizing the encompassed tissue and lesion 86. A measurement catheter90 having a number of gradations 92 with known distances may be advancedthrough hood 12 and into lumen 72. With the purging fluid introducedthrough hood 12 and into lumen 72, the markings on catheter 90 may beviewed and compared to the lesion 86 directly to provide a more accuratemeasurement of the lesion length than provided by a fluoroscopic imagealone.

FIG. 9B shows another example where one or more measurement baskets orexpandable members 92, 94, 96, 98 (e.g., wire or mesh baskets,distensible membranes, etc.) may be utilized to measure an innerdiameter of the vessel. Expandable baskets or members each having aknown expanded diameter may be positioned along a support catheter 100and advanced distally from hood 12 and into lumen 72 to measure adiameter of the vessel interior. The one or more members may bepositioned along catheter 100 in increasing order of diameter size withcolors, designs, markings, or other visual indications used to identifyeach particular member. Although four members 92, 94, 96, 98 are shownin the example, as few as one member or greater than four members may beutilized. Moreover, each subsequent member may be stepped in diametersize by a predetermined amount as desired. The members may be passedthrough the vessel ostium while under visualization in increasing orderof diameter until the expanded basket is compressed or unable tocannulate the ostium OS. The inner diameter of the vessel can thus becalculated by considering the diameter of the member which is blockedfrom entering ostium OS. With the calculated length and diameter of thevessel and lesion to be treated, an appropriate stent 84 may be selectedfor placement at the ostial lesion 86.

In use, catheter 100 may be advanced through hood 12 with the one ormore measurement baskets or expandable members 92, 94, 96, 98 configuredin a delivery profile while constrained within sheath 102, as shown inthe detail side view of FIG. 10A. Sheath 102 may be retracted, asindicated by the arrows, or catheter 100 may be advanced distally untileach respective member is deployed and expanded, as shown in FIG. 10B,until all the members 92, 94, 96, 98 or an appropriate number of membershave been deployed and expanded within the vessel lumen and/or proximateto the ostium OS, as shown in FIG. 10C.

In another variation, FIGS. 11A to 11E show cross-sectional views of adeployment catheter 16 utilizing an inflatable visualization balloonassembly 110 which remains enclosed rather than an open hood 12. Thestent assembly 80 may be utilized with the visualization balloon 110 andpositioned either through a lumen defined through the visualizationballoon 110 or distally upon balloon 82, which in this example may becoupled as a separate balloon or integrated with visualization balloon110 as a single balloon assembly, as shown in FIG. 11A. Balloon 82 inthis variation may comprise a thin, tube-like deployment balloon withstent 84 crimped around it and with the relatively larger transparentvisualization balloon 110 positioned proximally. Imager 34 may bepositioned within balloon 110 for imaging through the balloons 110and/or 82 for visualizing the ostium OS as well as the vessel walls.

With guidewire 70 advanced through the lumen 72 of, e.g., right coronaryartery RCA, stent 84 and balloon 82 maybe inserted at least partiallyinto the right coronary artery RCA. The proximal visualization balloon110 may be inflated and pushed distally until the balloon surface isfirmly in contact with the vessel ostium OS and free from blood betweenthe balloon-tissue interface to visualize the ostium OS, as shown inFIG. 11B. The positioning of the stent 84 with respect to the ostiallesion 86 can thus be viewed with imaging element 34 inside thevisualization balloon 110. Stent 84 can then be manipulated by pushingor pulling the balloon system against the ostial lesion 86. With theinflated visualization balloon 110 firmly pressing against the ostiumOS, the operator may also be able to ensure that the stent 84 is notplaced too proximally such that parts of the stent 84 is not protrudinginto the aortic lumen which can cause thrombus or other complications.

Upon visual confirmation that the stent 84 is positioned at its desiredlocation and overlapping the ostial lesion 86, the deployment balloon 82may be inflated until the stent 84 attains its stable configuration andis securely placed within the vessel, as shown in FIG. 11C, while theentire procedure is viewed under direct visualization with imagingelement 34. Upon the successful placement of the stent 84 at the site ofostial lesion 86, one or both balloon 82 and/or visualization balloon110 may be deflated and reduced to their original configuration andwithdrawn, as shown in FIG. 11D. The assembly may then be withdrawnalong with the guidewire 70 leaving behind the stent 84, as shown inFIG. 11E.

In yet another variation, FIG. 12A shows a side view of a deploymentcatheter 16 with hood 12 having an angled interface 120 which is angledrelative to catheter 16. In this variation, an asymmetric, slanted hood12 may be used to facilitate navigation within the aorta as the hood 12may be better able to engage against a tissue region or ostium andestablish visualization without the need to steer and/or articulate thecatheter shaft perpendicularly within the narrow aorta lumen. Asillustrated in FIG. 12B, angled interface 120 can be used to access theright coronary artery RCA without having to steer/articulate thedeployment catheter 16 perpendicularly relative to ostium OS. A sectionof catheter 16 proximal to hood 12 can also optionally comprise apassive pre-shaped bend in place of an actively steerable section toassist the hood 12 in visualizing and accessing the coronary arteries.

The applications of the disclosed invention discussed above are notlimited to certain treatments or regions of the body, but may includeany number of other treatments and areas of the body. Modification ofthe above-described methods and devices for carrying out the invention,and variations of aspects of the invention that are obvious to those ofskill in the arts are intended to be within the scope of thisdisclosure. Moreover, various combinations of aspects between examplesare also contemplated and are considered to be within the scope of thisdisclosure as well.

1-18. (canceled)
 19. A tissue manipulation system, comprising: areconfigurable hood structure with a distal end, the structure having alow profile delivery configuration and an expanded deployedconfiguration which defines an open area bounded at least in part by thestructure and by an interface surface extending across the hoodstructure distal end, the open area in fluid communication with anenvironment external to the hood structure; a catheter in communicationwith the open area such that introduction of a fluid through thecatheter purges the open area of bodily fluid, wherein the catheterextends along a longitudinal axis and wherein the interface surface isslanted relative to the longitudinal axis when the hood structure is inthe expanded deployed configuration; and an imaging element positionedon the hood structure such that the open area is visualized through thefluid by the element.
 20. The system of claim 19 wherein an aperture isdefined through the interface surface and the aperture isnon-perpendicular to the longitudinal axis of the catheter.
 21. Thesystem of claim 20 wherein the aperture has an aperture diameter smallerthan an outer lip diameter of the hood structure in the expandeddeployed configuration.
 22. The system of claim 19 wherein the hoodstructure is asymmetric.
 23. The system of claim 19 wherein the catheterincludes a steerable segment proximal to the hood structure.
 24. Thesystem of claim 23 wherein the steerable segment includes pivotallyconnected links.
 25. The system of claim 19 wherein the catheterincludes a passively pre-shaped bend proximal to the hood structure. 26.The system of claim 19 further comprising a scaffold structuresupporting the reconfigurable hood structure.
 27. The system of claim 26wherein the hood structure is asymmetric and wherein one arm of thescaffold structure has a different length from a second arm of thescaffold structure.
 28. The system of claim 26 wherein the imagingelement is coupled to the scaffold structure.